Re: Rack and Pinion

> Yes dave with DP pitch gears there will be some error.
> A 12 pitch rack will be 0.2618" between teeth.
>
> If you need a very accurate linear movemnet you use circular pitch

gears and racks, CP, instead of DP

> Nearest to 12 DP is 1/4" CP whose pitch is 0.250" or equal to

12.5664 DP

> Next common is 1/5" CP whose pitch is 0.200" or equal to 15.7080 DP
>
> John S.

Ah... a clue...

I am using McMaster Carr and they offer PD not CP gears.

The racks I found also use PD and not CP, but of course, your
suggestion makes sense. There has to be a scale that results in a
interger linear movement based on the rack instead of the gear.

Dave